Raising the voltage
Distribution voltage110 V · 1973
Scroll ↓Nº 01 — Never enough power
1948 —After liberation, electricity in the South was always scarce. When the North cut off the power it had been sending south in May 1948, the shortage only deepened. How could so precious a resource be delivered with less of it lost?
Homes and factories were supplied at 110 volts. At low voltage, delivering the same power takes more current, and more of that power is lost as heat in the wires. Electricity was leaking away before it ever reached the house.
Han Man Choon, who had brought control-engineering ideas into power systems, set out the theoretical case in the early 1970s for raising distribution voltage to 220/380 volts, and showed by calculation how much economic benefit the change would bring.
Double the voltage,
a quarter of the loss
For the same power, current falls as voltage rises (P = V × I). The power lost as heat in a line grows with the square of the current (Ploss = I²R).
So raising 110 volts to 220 halves the current and, on the same wire, cuts the loss to a quarter in theory.
plantHome
Simplified theoretical values for the same power over the same wire. Real-world savings depend on equipment and load.
The voltage conversion, 1973–2005
Years 2005
In 1973, when income per person stood at around 400 dollars a year, the Korea Electric Power Corporation began converting the country to 220 volts. The work of switching distribution equipment nationwide was completed in 2005.
KEPCO later described his proposal as a breakthrough: it achieved the effect of an additional power plant without adding generating capacity.
Today, the sockets of this country carry 220 volts.